X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Ftypecheck%2FTcDeriv.lhs;h=156a180ef6725327b980da87ddbcc1c1d3dc8d26;hb=461f1fb54915b564141ec07ce6f2ea284dc6cea8;hp=5e7d91e4ca92e8c55e30b41dd0cd57468df017ae;hpb=5cf27e8f1731c52fe63a5b9615f927484164c61b;p=ghc-hetmet.git diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs index 5e7d91e..156a180 100644 --- a/ghc/compiler/typecheck/TcDeriv.lhs +++ b/ghc/compiler/typecheck/TcDeriv.lhs @@ -1,59 +1,62 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[TcDeriv]{Deriving} Handles @deriving@ clauses on @data@ declarations. \begin{code} +module TcDeriv ( tcDeriving ) where + #include "HsVersions.h" -module TcDeriv ( tcDeriving ) where +import HsSyn ( HsBinds(..), MonoBinds(..), collectMonoBinders ) +import RdrHsSyn ( RdrNameMonoBinds ) +import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds ) +import CmdLineOpts ( opt_D_dump_deriv ) -import Ubiq - -import HsSyn ( FixityDecl, Sig, HsBinds(..), Bind(..), MonoBinds(..), - GRHSsAndBinds, Match, HsExpr, HsLit, InPat, - ArithSeqInfo, Fake, MonoType ) -import HsPragmas ( InstancePragmas(..) ) -import RnHsSyn ( RenamedHsBinds(..), RenamedFixityDecl(..) ) -import TcHsSyn ( TcIdOcc ) - -import TcMonad hiding ( rnMtoTcM ) -import Inst ( InstOrigin(..), InstanceMapper(..) ) -import TcEnv ( getEnv_TyCons ) -import TcKind ( TcKind ) ---import TcGenDeriv -- Deriv stuff -import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, buildInstanceEnvs ) +import TcMonad +import Inst ( InstanceMapper ) +import TcEnv ( getEnvTyCons ) +import TcGenDeriv -- Deriv stuff +import TcInstUtil ( InstInfo(..), buildInstanceEnvs ) import TcSimplify ( tcSimplifyThetas ) -import RnMonad -import RnUtils ( RnEnv(..) ) -import RnBinds ( rnMethodBinds, rnTopBinds ) - -import Bag ( emptyBag{-ToDo:rm-}, Bag, isEmptyBag, unionBags, listToBag ) -import Class ( GenClass, classKey ) -import CmdLineOpts ( opt_CompilingPrelude ) -import ErrUtils ( pprBagOfErrors, addErrLoc, Error(..) ) -import Id ( dataConSig, dataConArity ) -import Maybes ( assocMaybe, maybeToBool, Maybe(..) ) -import Outputable -import PprType ( GenType, GenTyVar, GenClass, TyCon ) -import PprStyle -import Pretty -import SrcLoc ( mkGeneratedSrcLoc, mkUnknownSrcLoc, SrcLoc ) +import RnBinds ( rnMethodBinds, rnTopMonoBinds ) +import RnEnv ( newDFunName, bindLocatedLocalsRn ) +import RnMonad ( RnNameSupply, + renameSourceCode, thenRn, mapRn, returnRn ) + +import Bag ( Bag, emptyBag, unionBags, listToBag ) +import Class ( classKey, Class ) +import ErrUtils ( dumpIfSet, Message, pprBagOfErrors ) +import MkId ( mkDictFunId ) +import Id ( mkVanillaId ) +import DataCon ( dataConArgTys, isNullaryDataCon, isExistentialDataCon ) +import PrelInfo ( needsDataDeclCtxtClassKeys ) +import Maybes ( maybeToBool, catMaybes ) +import Module ( ModuleName ) +import Name ( isLocallyDefined, getSrcLoc, + Name, NamedThing(..), + OccName, nameOccName + ) +import RdrName ( RdrName ) +import RnMonad ( Fixities ) +import SrcLoc ( mkGeneratedSrcLoc, SrcLoc ) import TyCon ( tyConTyVars, tyConDataCons, tyConDerivings, - maybeTyConSingleCon, isEnumerationTyCon, TyCon ) -import Type ( GenType(..), TauType(..), mkTyVarTys, applyTyCon, - mkSigmaTy, mkDictTy, isPrimType, instantiateTy, - getAppTyCon, getAppDataTyCon + tyConTheta, maybeTyConSingleCon, isDataTyCon, + isEnumerationTyCon, isAlgTyCon, TyCon ) -import TyVar ( GenTyVar ) -import UniqFM ( emptyUFM ) -import Unique -- Keys stuff -import Util ( zipWithEqual, zipEqual, sortLt, removeDups, - thenCmp, cmpList, panic, pprPanic, pprPanic# +import Type ( TauType, mkTyVarTys, mkTyConApp, + mkSigmaTy, mkDictTy, isUnboxedType, + splitAlgTyConApp, classesToPreds ) +import TysWiredIn ( voidTy ) +import Var ( TyVar ) +import Unique -- Keys stuff +import Bag ( bagToList ) +import Util ( zipWithEqual, sortLt, removeDups, assoc, thenCmp ) +import Outputable \end{code} %************************************************************************ @@ -69,6 +72,10 @@ Consider | C3 (T a a) deriving (Eq) +[NOTE: See end of these comments for what to do with + data (C a, D b) => T a b = ... +] + We want to come up with an instance declaration of the form instance (Ping a, Pong b, ...) => Eq (T a b) where @@ -142,11 +149,36 @@ type DerivEqn = (Class, TyCon, [TyVar], DerivRhs) -- NEW: it's convenient to re-use InstInfo -- We'll "panic" out some fields... -type DerivRhs = [(Class, TauType)] -- Same as a ThetaType! +type DerivRhs = [(Class, [TauType])] -- Same as a ThetaType! type DerivSoln = DerivRhs \end{code} + +A note about contexts on data decls +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Consider + + data (RealFloat a) => Complex a = !a :+ !a deriving( Read ) + +We will need an instance decl like: + + instance (Read a, RealFloat a) => Read (Complex a) where + ... + +The RealFloat in the context is because the read method for Complex is bound +to construct a Complex, and doing that requires that the argument type is +in RealFloat. + +But this ain't true for Show, Eq, Ord, etc, since they don't construct +a Complex; they only take them apart. + +Our approach: identify the offending classes, and add the data type +context to the instance decl. The "offending classes" are + + Read, Enum? + + %************************************************************************ %* * \subsection[TcDeriv-driver]{Top-level function for \tr{derivings}} @@ -154,29 +186,27 @@ type DerivSoln = DerivRhs %************************************************************************ \begin{code} -tcDeriving :: Module -- name of module under scrutiny - -> RnEnv -- for "renaming" bits of generated code +tcDeriving :: ModuleName -- name of module under scrutiny + -> Fixities -- for the deriving code (Show/Read.) + -> RnNameSupply -- for "renaming" bits of generated code -> Bag InstInfo -- What we already know about instances - -> [RenamedFixityDecl] -- Fixity info; used by Read and Show -> TcM s (Bag InstInfo, -- The generated "instance decls". - RenamedHsBinds, -- Extra generated bindings - PprStyle -> Pretty) -- Printable derived instance decls; - -- for debugging via -ddump-derivings. + RenamedHsBinds) -- Extra generated bindings -tcDeriving modname rn_env inst_decl_infos_in fixities - = returnTc (trace "tcDeriving:ToDo" (emptyBag, EmptyBinds, \ x -> ppNil)) -{- LATER: +tcDeriving modname fixs rn_name_supply inst_decl_infos_in + = recoverTc (returnTc (emptyBag, EmptyBinds)) $ -tcDeriving modname rn_env inst_decl_infos_in fixities - = -- Fish the "deriving"-related information out of the TcEnv + -- Fish the "deriving"-related information out of the TcEnv -- and make the necessary "equations". - makeDerivEqns `thenTc` \ eqns -> + makeDerivEqns `thenTc` \ eqns -> + if null eqns then + returnTc (emptyBag, EmptyBinds) + else -- Take the equation list and solve it, to deliver a list of -- solutions, a.k.a. the contexts for the instance decls -- required for the corresponding equations. - solveDerivEqns inst_decl_infos_in eqns - `thenTc` \ new_inst_infos -> + solveDerivEqns inst_decl_infos_in eqns `thenTc` \ new_inst_infos -> -- Now augment the InstInfos, adding in the rather boring -- actual-code-to-do-the-methods binds. We may also need to @@ -184,46 +214,50 @@ tcDeriving modname rn_env inst_decl_infos_in fixities -- "con2tag" and/or "tag2con" functions. We do these -- separately. - gen_taggery_Names eqns `thenTc` \ nm_alist_etc -> - let - nm_alist = [ (pn, n) | (pn,n,_,_) <- nm_alist_etc ] - - -- We have the renamer's final "name funs" in our hands - -- (they were passed in). So we can handle ProtoNames - -- that refer to anything "out there". But our generated - -- code may also mention "con2tag" (etc.). So we need - -- to augment to "name funs" to include those. - (rn_val_gnf, rn_tc_gnf) = renamer_name_funs - - deriv_val_gnf pname = case (assoc_maybe nm_alist pname) of - Just xx -> Just xx - Nothing -> rn_val_gnf pname + gen_taggery_Names new_inst_infos `thenTc` \ nm_alist_etc -> - deriver_name_funs = (deriv_val_gnf, rn_tc_gnf) - assoc_maybe [] _ = Nothing - assoc_maybe ((k,v) : vs) key - = if k `eqProtoName` key then Just v else assoc_maybe vs key + let + extra_mbind_list = map gen_tag_n_con_monobind nm_alist_etc + extra_mbinds = foldr AndMonoBinds EmptyMonoBinds extra_mbind_list + method_binds_s = map (gen_bind fixs) new_inst_infos + mbinders = bagToList (collectMonoBinders extra_mbinds) + + -- Rename to get RenamedBinds. + -- The only tricky bit is that the extra_binds must scope over the + -- method bindings for the instances. + (dfun_names_w_method_binds, rn_extra_binds) + = renameSourceCode modname rn_name_supply ( + bindLocatedLocalsRn (ptext (SLIT("deriving"))) mbinders $ \ _ -> + rnTopMonoBinds extra_mbinds [] `thenRn` \ (rn_extra_binds, _) -> + mapRn rn_one method_binds_s `thenRn` \ dfun_names_w_method_binds -> + returnRn (dfun_names_w_method_binds, rn_extra_binds) + ) + rn_one (cl_nm, tycon_nm, meth_binds) + = newDFunName (cl_nm, tycon_nm) + mkGeneratedSrcLoc `thenRn` \ dfun_name -> + rnMethodBinds meth_binds `thenRn` \ (rn_meth_binds, _) -> + returnRn (dfun_name, rn_meth_binds) + + really_new_inst_infos = zipWith gen_inst_info + new_inst_infos + dfun_names_w_method_binds + + ddump_deriv = ddump_deriving really_new_inst_infos rn_extra_binds in - gen_tag_n_con_binds deriver_rn_env nm_alist_etc `thenTc` \ extra_binds -> - - mapTc (gen_inst_info maybe_mod fixities deriver_rn_env) new_inst_infos - `thenTc` \ really_new_inst_infos -> + ioToTc (dumpIfSet opt_D_dump_deriv "Derived instances" ddump_deriv) `thenTc_` - returnTc (listToBag really_new_inst_infos, - extra_binds, - ddump_deriving really_new_inst_infos extra_binds) + returnTc (listToBag really_new_inst_infos, rn_extra_binds) where - maybe_mod = if opt_CompilingPrelude then Nothing else Just mod_name - - ddump_deriving :: [InstInfo] -> RenamedHsBinds -> (PprStyle -> Pretty) - - ddump_deriving inst_infos extra_binds sty - = ppAboves ((map pp_info inst_infos) ++ [ppr sty extra_binds]) + ddump_deriving :: [InstInfo] -> RenamedHsBinds -> SDoc + ddump_deriving inst_infos extra_binds + = vcat (map pp_info inst_infos) $$ ppr extra_binds where - pp_info (InstInfo clas tvs ty inst_decl_theta _ _ _ mbinds _ _ _ _) - = ppAbove (ppr sty (mkSigmaTy tvs inst_decl_theta (mkDictTy clas ty))) - (ppr sty mbinds) + pp_info (InstInfo clas tvs [ty] inst_decl_theta _ mbinds _ _) + = ppr (mkSigmaTy tvs inst_decl_theta' (mkDictTy clas [ty])) + $$ + ppr mbinds + where inst_decl_theta' = classesToPreds inst_decl_theta \end{code} @@ -252,75 +286,87 @@ all those. makeDerivEqns :: TcM s [DerivEqn] makeDerivEqns - = tcGetEnv `thenNF_Tc` \ env -> - let - tycons = getEnv_TyCons env - think_about_deriving = need_deriving tycons - in - mapTc (chk_out think_about_deriving) think_about_deriving `thenTc_` + = tcGetEnv `thenNF_Tc` \ env -> let - (derive_these, _) = removeDups cmp_deriv think_about_deriving - eqns = map mk_eqn derive_these + local_data_tycons = filter (\tc -> isLocallyDefined tc && isAlgTyCon tc) + (getEnvTyCons env) + + think_about_deriving = need_deriving local_data_tycons + (derive_these, _) = removeDups cmp_deriv think_about_deriving + eqns = map mk_eqn derive_these in - returnTc eqns + if null local_data_tycons then + returnTc [] -- Bale out now + else + mapTc mk_eqn derive_these `thenTc` \ maybe_eqns -> + returnTc (catMaybes maybe_eqns) where ------------------------------------------------------------------ need_deriving :: [TyCon] -> [(Class, TyCon)] - -- find the tycons that have `deriving' clauses + -- find the tycons that have `deriving' clauses; need_deriving tycons_to_consider - = foldr ( \ tycon acc -> - case (tyConDerivings tycon) of - [] -> acc - cs -> [ (clas,tycon) | clas <- cs ] ++ acc - ) + = foldr (\ tycon acc -> [(clas,tycon) | clas <- tyConDerivings tycon] ++ acc) [] tycons_to_consider ------------------------------------------------------------------ - chk_out :: [(Class, TyCon)] -> (Class, TyCon) -> TcM s () - chk_out whole_deriving_list this_one@(clas, tycon) - = let - clas_key = classKey clas - in - - -- Are things OK for deriving Enum (if appropriate)? - checkTc (clas_key == enumClassKey && not (isEnumerationTyCon tycon)) - (derivingEnumErr tycon) `thenTc_` - - -- Are things OK for deriving Ix (if appropriate)? - checkTc (clas_key == ixClassKey - && not (isEnumerationTyCon tycon - || maybeToBool (maybeTyConSingleCon tycon))) - (derivingIxErr tycon) - - ------------------------------------------------------------------ - cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> TAG_ + cmp_deriv :: (Class, TyCon) -> (Class, TyCon) -> Ordering cmp_deriv (c1, t1) (c2, t2) - = (c1 `cmp` c2) `thenCmp` (t1 `cmp` t2) + = (c1 `compare` c2) `thenCmp` (t1 `compare` t2) ------------------------------------------------------------------ - mk_eqn :: (Class, TyCon) -> DerivEqn + mk_eqn :: (Class, TyCon) -> NF_TcM s (Maybe DerivEqn) -- we swizzle the tyvars and datacons out of the tycon -- to make the rest of the equation mk_eqn (clas, tycon) - = (clas, tycon, tyvars, constraints) + = case chk_out clas tycon of + Just err -> addErrTc err `thenNF_Tc_` + returnNF_Tc Nothing + Nothing -> returnNF_Tc (Just (clas, tycon, tyvars, constraints)) where + clas_key = classKey clas tyvars = tyConTyVars tycon -- ToDo: Do we need new tyvars ??? tyvar_tys = mkTyVarTys tyvars data_cons = tyConDataCons tycon - constraints = concat (map mk_constraints data_cons) + + constraints = extra_constraints ++ concat (map mk_constraints data_cons) + + -- "extra_constraints": see notes above about contexts on data decls + extra_constraints + | offensive_class = tyConTheta tycon + | otherwise = [] + where + offensive_class = clas_key `elem` needsDataDeclCtxtClassKeys mk_constraints data_con - = [ (clas, instantiateTy inst_env arg_ty) - | arg_ty <- arg_tys, - not (isPrimType arg_ty) -- No constraints for primitive types + = [ (clas, [arg_ty]) + | arg_ty <- instd_arg_tys, + not (isUnboxedType arg_ty) -- No constraints for unboxed types? ] where - (con_tyvars, _, arg_tys, _) = dataConSig data_con - inst_env = zipEqual "mk_eqn" con_tyvars tyvar_tys - -- same number of tyvars in data constr and type constr! + instd_arg_tys = dataConArgTys data_con tyvar_tys + + ------------------------------------------------------------------ + chk_out :: Class -> TyCon -> Maybe Message + chk_out clas tycon + | clas_key == enumClassKey && not is_enumeration = bog_out nullary_why + | clas_key == boundedClassKey && not is_enumeration_or_single = bog_out single_nullary_why + | clas_key == ixClassKey && not is_enumeration_or_single = bog_out single_nullary_why + | any isExistentialDataCon (tyConDataCons tycon) = Just (existentialErr clas tycon) + | otherwise = Nothing + where + clas_key = classKey clas + + is_enumeration = isEnumerationTyCon tycon + is_single_con = maybeToBool (maybeTyConSingleCon tycon) + is_enumeration_or_single = is_enumeration || is_single_con + + single_nullary_why = SLIT("one constructor data type or type with all nullary constructors expected") + nullary_why = SLIT("data type with all nullary constructors expected") + + bog_out why = Just (derivingThingErr clas tycon why) \end{code} %************************************************************************ @@ -334,11 +380,11 @@ terms, which is the final correct RHS for the corresponding original equation. \begin{itemize} \item -Each (k,UniTyVarTemplate tv) in a solution constrains only a type +Each (k,TyVarTy tv) in a solution constrains only a type variable, tv. \item -The (k,UniTyVarTemplate tv) pairs in a solution are canonically +The (k,TyVarTy tv) pairs in a solution are canonically ordered by sorting on type varible, tv, (major key) and then class, k, (minor key) \end{itemize} @@ -358,90 +404,88 @@ solveDerivEqns inst_decl_infos_in orig_eqns initial_solutions :: [DerivSoln] initial_solutions = [ [] | _ <- orig_eqns ] + ------------------------------------------------------------------ -- iterateDeriv calculates the next batch of solutions, -- compares it with the current one; finishes if they are the -- same, otherwise recurses with the new solutions. - + -- It fails if any iteration fails iterateDeriv :: [DerivSoln] ->TcM s [InstInfo] - iterateDeriv current_solns + = checkNoErrsTc (iterateOnce current_solns) `thenTc` \ (new_inst_infos, new_solns) -> + if (current_solns == new_solns) then + returnTc new_inst_infos + else + iterateDeriv new_solns + + ------------------------------------------------------------------ + iterateOnce current_solns = -- Extend the inst info from the explicit instance decls -- with the current set of solutions, giving a add_solns inst_decl_infos_in orig_eqns current_solns - `thenTc` \ (new_inst_infos, inst_mapper) -> - - -- Simplify each RHS, using a DerivingOrigin containing an - -- inst_mapper reflecting the previous solution + `thenNF_Tc` \ (new_inst_infos, inst_mapper) -> let - mk_deriv_origin clas ty - = DerivingOrigin inst_mapper clas tycon - where - (tycon,_) = getAppTyCon ty + class_to_inst_env cls = inst_mapper cls in - listTc [ tcSimplifyThetas mk_deriv_origin rhs - | (_, _, _, rhs) <- orig_eqns - ] `thenTc` \ next_solns -> + -- Simplify each RHS + + listTc [ tcAddErrCtxt (derivCtxt tc) $ + tcSimplifyThetas class_to_inst_env deriv_rhs + | (_,tc,_,deriv_rhs) <- orig_eqns ] `thenTc` \ next_solns -> -- Canonicalise the solutions, so they compare nicely let canonicalised_next_solns - = [ sortLt lt_rhs next_soln | next_soln <- next_solns ] in - - if current_solns `eq_solns` canonicalised_next_solns then - returnTc new_inst_infos - else - iterateDeriv canonicalised_next_solns - - where - ------------------------------------------------------------------ - lt_rhs r1 r2 = case cmp_rhs r1 r2 of { LT_ -> True; _ -> False } - eq_solns s1 s2 = case cmp_solns s1 s2 of { EQ_ -> True; _ -> False } - cmp_solns s1 s2 = cmpList (cmpList cmp_rhs) s1 s2 - cmp_rhs (c1, TyVarTy tv1) (c2, TyVarTy tv2) - = (tv1 `cmp` tv2) `thenCmp` (c1 `cmp` c2) -#ifdef DEBUG - cmp_rhs other_1 other_2 - = pprPanic# "tcDeriv:cmp_rhs:" (ppCat [ppr PprDebug other_1, ppr PprDebug other_2]) -#endif - + = [ sortLt (<) next_soln | next_soln <- next_solns ] + in + returnTc (new_inst_infos, canonicalised_next_solns) \end{code} \begin{code} -add_solns :: FAST_STRING - -> Bag InstInfo -- The global, non-derived ones +add_solns :: Bag InstInfo -- The global, non-derived ones -> [DerivEqn] -> [DerivSoln] - -> TcM s ([InstInfo], -- The new, derived ones - InstanceMapper) + -> NF_TcM s ([InstInfo], -- The new, derived ones + InstanceMapper) -- the eqns and solns move "in lockstep"; we have the eqns -- because we need the LHS info for addClassInstance. add_solns inst_infos_in eqns solns - = buildInstanceEnvs all_inst_infos `thenTc` \ inst_mapper -> - returnTc (new_inst_infos, inst_mapper) + + = discardErrsTc (buildInstanceEnvs all_inst_infos) `thenNF_Tc` \ inst_mapper -> + -- We do the discard-errs so that we don't get repeated error messages + -- about duplicate instances. + -- They'll appear later, when we do the top-level buildInstanceEnvs. + + returnNF_Tc (new_inst_infos, inst_mapper) where new_inst_infos = zipWithEqual "add_solns" mk_deriv_inst_info eqns solns all_inst_infos = inst_infos_in `unionBags` listToBag new_inst_infos mk_deriv_inst_info (clas, tycon, tyvars, _) theta - = InstInfo clas tyvars (applyTyCon tycon (mkTyVarTys tyvars)) + = InstInfo clas tyvars [mkTyConApp tycon (mkTyVarTys tyvars)] theta - theta -- Blarg. This is the dfun_theta slot, - -- which is needed by buildInstanceEnv; - -- This works ok for solving the eqns, and - -- gen_eqns sets it to its final value - -- (incl super class dicts) before we - -- finally return it. -#ifdef DEBUG - (panic "add_soln:dfun_id") (panic "add_soln:const_meth_ids") - (panic "add_soln:binds") (panic "add_soln:from_here") - (panic "add_soln:modname") mkGeneratedSrcLoc - (panic "add_soln:upragmas") -#else - bottom bottom bottom bottom bottom mkGeneratedSrcLoc bottom + dummy_dfun_id + (my_panic "binds") (getSrcLoc tycon) + (my_panic "upragmas") where - bottom = panic "add_soln" -#endif + dummy_dfun_id + = mkVanillaId (getName tycon) dummy_dfun_ty + -- The name is getSrcLoc'd in an error message + + theta' = classesToPreds theta + dummy_dfun_ty = mkSigmaTy tyvars theta' voidTy + -- All we need from the dfun is its "theta" part, used during + -- equation simplification (tcSimplifyThetas). The final + -- dfun_id will have the superclass dictionaries as arguments too, + -- but that'll be added after the equations are solved. For now, + -- it's enough just to make a dummy dfun with the simple theta part. + -- + -- The part after the theta is dummied here as voidTy; actually it's + -- (C (T a b)), but it doesn't seem worth constructing it. + -- We can't leave it as a panic because to get the theta part we + -- have to run down the type! + + my_panic str = panic "add_soln" -- pprPanic ("add_soln:"++str) (hsep [char ':', ppr clas, ppr tycon]) \end{code} %************************************************************************ @@ -465,8 +509,7 @@ We want derived instances of @Eq@ and @Ord@ (both v common) to be ``you-couldn't-do-better-by-hand'' efficient. \item -Deriving @Text@---also pretty common, usually just for -@show@---should also be reasonable good code. +Deriving @Show@---also pretty common--- should also be reasonable good code. \item Deriving for the other classes isn't that common or that big a deal. @@ -476,13 +519,13 @@ PRAGMATICS: \begin{itemize} \item -Deriving @Ord@ is done mostly with our non-standard @tagCmp@ method. +Deriving @Ord@ is done mostly with the 1.3 @compare@ method. \item -Deriving @Eq@ also uses @tagCmp@, if we're deriving @Ord@, too. +Deriving @Eq@ also uses @compare@, if we're deriving @Ord@, too. \item -We {\em normally} generated code only for the non-defaulted methods; +We {\em normally} generate code only for the non-defaulted methods; there are some exceptions for @Eq@ and (especially) @Ord@... \item @@ -491,7 +534,6 @@ constructor's numeric (@Int#@) tag. These are generated by @gen_tag_n_con_binds@, and the heuristic for deciding if one of these is around is given by @hasCon2TagFun@. - The examples under the different sections below will make this clearer. @@ -500,114 +542,78 @@ Much less often (really just for deriving @Ix@), we use a @_tag2con_@ function. See the examples. \item -We use Pass~4 of the renamer!!! Reason: we're supposed to be +We use the renamer!!! Reason: we're supposed to be producing @RenamedMonoBinds@ for the methods, but that means producing correctly-uniquified code on the fly. This is entirely possible (the @TcM@ monad has a @UniqueSupply@), but it is painful. -So, instead, we produce @ProtoNameMonoBinds@ then heave 'em through +So, instead, we produce @RdrNameMonoBinds@ then heave 'em through the renamer. What a great hack! \end{itemize} \begin{code} -gen_inst_info :: Maybe Module -- Module name; Nothing => Prelude - -> [RenamedFixityDecl] -- all known fixities; - -- may be needed for Text - -> RnEnv -- lookup stuff for names we may use - -> InstInfo -- the main stuff to work on - -> TcM s InstInfo -- the gen'd (filled-in) "instance decl" - -gen_inst_info modname fixities deriver_rn_env - info@(InstInfo clas tyvars ty inst_decl_theta _ _ _ _ _ _ locn _) +-- Generate the method bindings for the required instance +-- (paired with class name, as we need that when generating dict +-- names.) +gen_bind :: Fixities -> InstInfo -> ({-class-}OccName, {-tyCon-}OccName, RdrNameMonoBinds) +gen_bind fixities (InstInfo clas _ [ty] _ _ _ _ _) + | not from_here + = (clas_nm, tycon_nm, EmptyMonoBinds) + | ckey == showClassKey + = (clas_nm, tycon_nm, gen_Show_binds fixities tycon) + | ckey == readClassKey + = (clas_nm, tycon_nm, gen_Read_binds fixities tycon) + | otherwise + = (clas_nm, tycon_nm, + assoc "gen_bind:bad derived class" + [(eqClassKey, gen_Eq_binds) + ,(ordClassKey, gen_Ord_binds) + ,(enumClassKey, gen_Enum_binds) + ,(boundedClassKey, gen_Bounded_binds) + ,(ixClassKey, gen_Ix_binds) + ] + ckey + tycon) + where + clas_nm = nameOccName (getName clas) + tycon_nm = nameOccName (getName tycon) + from_here = isLocallyDefined tycon + (tycon,_,_) = splitAlgTyConApp ty + ckey = classKey clas + + +gen_inst_info :: InstInfo + -> (Name, RenamedMonoBinds) + -> InstInfo -- the gen'd (filled-in) "instance decl" + +gen_inst_info (InstInfo clas tyvars tys@(ty:_) inst_decl_theta _ _ locn _) + (dfun_name, meth_binds) = -- Generate the various instance-related Ids - mkInstanceRelatedIds - True {-from_here-} locn modname - NoInstancePragmas - clas tyvars ty - inst_decl_theta - [{-no user pragmas-}] - `thenTc` \ (dfun_id, dfun_theta, const_meth_ids) -> - - -- Generate the bindings for the new instance declaration, - -- rename it, and check for errors - let - (tycon,_,_) = getAppDataTyCon ty - - proto_mbinds - | clas_key == eqClassKey = gen_Eq_binds tycon - | clas_key == showClassKey = gen_Show_binds fixities tycon - | clas_key == ordClassKey = gen_Ord_binds tycon - | clas_key == enumClassKey = gen_Enum_binds tycon - | clas_key == ixClassKey = gen_Ix_binds tycon - | clas_key == readClassKey = gen_Read_binds fixities tycon - | clas_key == binaryClassKey = gen_Binary_binds tycon - | otherwise = panic "gen_inst_info:bad derived class" - in - rnMtoTcM deriver_rn_env ( - setExtraRn emptyUFM{-no fixities-} $ - rnMethodBinds clas_Name proto_mbinds - ) `thenNF_Tc` \ (mbinds, errs) -> - - if not (isEmptyBag errs) then - pprPanic "gen_inst_info:renamer errs!\n" - (ppAbove (pprBagOfErrors PprDebug errs) (ppr PprDebug proto_mbinds)) - else - --pprTrace "derived binds:" (ppr PprDebug proto_mbinds) $ - - -- All done - let - from_here = isLocallyDefined tycon -- If so, then from here - in - returnTc (InstInfo clas tyvars ty inst_decl_theta - dfun_theta dfun_id const_meth_ids - (if from_here then mbinds else EmptyMonoBinds) - from_here modname locn []) + InstInfo clas tyvars tys inst_decl_theta + dfun_id + meth_binds + locn [] where - clas_key = classKey clas - clas_Name - = let (mod, nm) = moduleNamePair clas in - ClassName clas_key (mkPreludeCoreName mod nm) [] + dfun_id = mkDictFunId dfun_name clas tyvars tys inst_decl_theta + + from_here = isLocallyDefined tycon + (tycon,_,_) = splitAlgTyConApp ty \end{code} + %************************************************************************ %* * -\subsection[TcGenDeriv-con2tag-tag2con]{Generating extra binds (@con2tag@ and @tag2con@)} +\subsection[TcDeriv-taggery-Names]{What con2tag/tag2con functions are available?} %* * %************************************************************************ + data Foo ... = ... con2tag_Foo :: Foo ... -> Int# tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int# maxtag_Foo :: Int -- ditto (NB: not unboxed) -\begin{code} -gen_tag_n_con_binds :: RnEnv - -> [(RdrName, RnName, TyCon, TagThingWanted)] - -> TcM s RenamedHsBinds - -gen_tag_n_con_binds deriver_rn_env nm_alist_etc - = let - proto_mbind_list = map gen_tag_n_con_monobind nm_alist_etc - proto_mbinds = foldr AndMonoBinds EmptyMonoBinds proto_mbind_list - in - - rnMtoTcM deriver_rn_env ( - setExtraRn emptyUFM{-no fixities-} $ - rnTopBinds (SingleBind (RecBind proto_mbinds)) - ) `thenNF_Tc` \ (binds, errs) -> - - if not (isEmptyBag errs) then - panic "gen_inst_info:renamer errs (2)!" - else - returnTc binds -\end{code} - -%************************************************************************ -%* * -\subsection[TcDeriv-taggery-Names]{What con2tag/tag2con functions are available?} -%* * -%************************************************************************ We have a @con2tag@ function for a tycon if: \begin{itemize} @@ -628,64 +634,70 @@ We're deriving @Enum@, or @Ix@ (enum type only???) If we have a @tag2con@ function, we also generate a @maxtag@ constant. \begin{code} -gen_taggery_Names :: [DerivEqn] - -> TcM s [(RdrName, RnName, -- for an assoc list - TyCon, -- related tycon +gen_taggery_Names :: [InstInfo] + -> TcM s [(RdrName, -- for an assoc list + TyCon, -- related tycon TagThingWanted)] -gen_taggery_Names eqns - = let - all_tycons = [ tc | (_, tc, _, _) <- eqns ] - (tycons_of_interest, _) = removeDups cmp all_tycons - in - foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far -> - foldlTc do_tag2con names_so_far tycons_of_interest +gen_taggery_Names inst_infos + = --pprTrace "gen_taggery:\n" (vcat [hsep [ppr c, ppr t] | (c,t) <- all_CTs]) $ + foldlTc do_con2tag [] tycons_of_interest `thenTc` \ names_so_far -> + foldlTc do_tag2con names_so_far tycons_of_interest where + all_CTs = [ (c, get_tycon ty) | (InstInfo c _ [ty] _ _ _ _ _) <- inst_infos ] + + get_tycon ty = case splitAlgTyConApp ty of { (tc, _, _) -> tc } + + all_tycons = map snd all_CTs + (tycons_of_interest, _) = removeDups compare all_tycons + do_con2tag acc_Names tycon - = if (we_are_deriving eqClassKey tycon - && any ( (== 0).dataConArity ) (tyConDataCons tycon)) - || (we_are_deriving ordClassKey tycon + | isDataTyCon tycon && + ((we_are_deriving eqClassKey tycon + && any isNullaryDataCon (tyConDataCons tycon)) + || (we_are_deriving ordClassKey tycon && not (maybeToBool (maybeTyConSingleCon tycon))) - || (we_are_deriving enumClassKey tycon) - || (we_are_deriving ixClassKey tycon) - then - tcGetUnique `thenNF_Tc` ( \ u -> - returnTc ((con2tag_PN tycon, ValName u (con2tag_FN tycon), tycon, GenCon2Tag) - : acc_Names) ) - else - returnTc acc_Names + || (we_are_deriving enumClassKey tycon) + || (we_are_deriving ixClassKey tycon)) + + = returnTc ((con2tag_RDR tycon, tycon, GenCon2Tag) + : acc_Names) + | otherwise + = returnTc acc_Names do_tag2con acc_Names tycon - = if (we_are_deriving enumClassKey tycon) - || (we_are_deriving ixClassKey tycon) - then - tcGetUnique `thenNF_Tc` \ u1 -> - tcGetUnique `thenNF_Tc` \ u2 -> - returnTc ( (tag2con_PN tycon, ValName u1 (tag2con_FN tycon), tycon, GenTag2Con) - : (maxtag_PN tycon, ValName u2 (maxtag_FN tycon), tycon, GenMaxTag) - : acc_Names) - else - returnTc acc_Names + | isDataTyCon tycon && + (we_are_deriving enumClassKey tycon || + we_are_deriving ixClassKey tycon + && isEnumerationTyCon tycon) + = returnTc ( (tag2con_RDR tycon, tycon, GenTag2Con) + : (maxtag_RDR tycon, tycon, GenMaxTag) + : acc_Names) + | otherwise + = returnTc acc_Names we_are_deriving clas_key tycon - = is_in_eqns clas_key tycon eqns + = is_in_eqns clas_key tycon all_CTs where is_in_eqns clas_key tycon [] = False - is_in_eqns clas_key tycon ((c,t,_,_):eqns) + is_in_eqns clas_key tycon ((c,t):cts) = (clas_key == classKey c && tycon == t) - || is_in_eqns clas_key tycon eqns + || is_in_eqns clas_key tycon cts \end{code} \begin{code} -derivingEnumErr :: TyCon -> Error -derivingEnumErr tycon - = addErrLoc (getSrcLoc tycon) "Can't derive an instance of `Enum'" ( \ sty -> - ppBesides [ppStr "type `", ppr sty tycon, ppStr "'"] ) - -derivingIxErr :: TyCon -> Error -derivingIxErr tycon - = addErrLoc (getSrcLoc tycon) "Can't derive an instance of `Ix'" ( \ sty -> - ppBesides [ppStr "type `", ppr sty tycon, ppStr "'"] ) --} +derivingThingErr :: Class -> TyCon -> FAST_STRING -> Message + +derivingThingErr clas tycon why + = sep [hsep [ptext SLIT("Can't make a derived instance of"), quotes (ppr clas)], + hsep [ptext SLIT("for the type"), quotes (ppr tycon)], + parens (ptext why)] + +existentialErr clas tycon + = sep [ptext SLIT("Can't derive any instances for type") <+> quotes (ppr tycon), + ptext SLIT("because it has existentially-quantified constructor(s)")] + +derivCtxt tycon + = ptext SLIT("When deriving classes for") <+> quotes (ppr tycon) \end{code}